import java.util.IdentityHashMap;

public class Term {
    enum Kind { VARIABLE, COMPOUND };
    Kind kind;
    public Term dereference() { return this; }
    public boolean contains(Term _) { return false; }
    public Term copy_term(IdentityHashMap<Term,Term> map) { return this; }
    public Stack<Term> fromPrologList() { return null; }
}
